Blue Topaz has the unique distinction of capturing the sky in a gemstone. Blue topaz was once the rarest color of the topaz's colors. Today, because of color enhancement techniques developed in the 1970's, it is the most common. The popular icy pastel blue color is the result of irradiating and heating colorless topaz in a nuclear reactor. The process of irradiation can take minutes or years. Lighter shades of blue, such as Sky-Blue, result from irradiation by electrons. The darker blue, "London Blue," is created by bombarding the stone with neutrons. Combining the electrons and neutrons, creates the "Swiss/Electric Blue." The heating part of the process stabilizes the color. Following irradiation with neutrons, residual radioactivity requires that the stones be stored, sometimes as much as a year, until it is safe to put them on the market.
The pale or colorless Topaz is mined primarily in Brazil , Sri Lanka , Nigeria , and China . Natural light blue topaz is also found in England (Cornwall), Northern Ireland and Scotland. In 1969, following the discovery in Texas of a small deposit of natural pale Blue Topaz Blue, it was named the state gem.
Topaz is a hard gemstone (8 on the Mohs scale), but it can be split with a single blow: It is a trait that it shares with diamond. It can be worn on a daily basis if it is "protected" from hard knocks that would damage it. Topaz is easily cleaned with a mild dishwashing soap, using a toothbrush to get to the dirt behind the stone.
Much like other stones, top also has legends attached to it. It's said that the topaz dispels enchantment. Ancient Greeks believed that topaz had the power to increase strength and make its wearer invisible in times of emergency. Topaz gemstones were said to change color in the presence of poisoned food or drink.
Early in 1998, a new type of enhanced topaz appeared, the surface of which had been color-enhanced turning the stone blue to greenish-blue, or emerald green, creating "mystic topaz." Most pink topaz are heat-treated yellow stones. Such stones are attractive but the treatment is not permanent. With their extremely thin coating they must be handled very gently as any scratch or abrasion can mar the surface layer.
Colored topaz is usually a step, or scissor-cut, because it brings out the color of even weakly colored stones. If a topaz has disordered inclusions, it is best cut as a cabochon.